LME by Hg 2

[Corgas]

In order to protect a BAHX (aka "cold box") from LME, we have started measuring Hg in the inlet gas.

Question 1) What's the minimimum amount of Hg that will cause LME? is there a published threshold value?

Question 2)What's the most effective non-destructive test (non-intrusive) to detect Hg in such equipment (completely insulated)?

Thanks,

Corgas

 

[SJones]

1) That which will condense liquid mercury under the operating conditions

2) Surely, trying to detect mercury is not an ALARP measure. If you have a susceptible material and liquid mercury will drop out, you have two options: change the material, or remove the mercury upstream

For aluminium, there will also be an amalgam corrosion risk if water is present.

Steve Jones
Materials & Corrosion Engineer

http://www.linkedin.com/pub/8/83b/b04

 

[EdStainless]

It depends on the alloys involved and the stress levels.
In general if there is free Hg then you have an issue.

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Plymouth Tube

 

[Corgas]

Mr. Jones,

even in the ppb range will cause LME?

Thanks,

 

[enmax]

Mercury in aluminium systems is a serious problem - one of the reasons that liquid mercury is banned from aircraft! In gas processing plants it's measured in ng (yes -nanograms!)/cubic metre). There is some backgound information here:

http://www.jmcatalysts.com/ptd/pdfs-uploaded/Mercury matters Dec 05.pdf

 

[Corgas]

enmax : Thanks for the info.

It all comes down to this : Based on the Hg coming in with the gas, when do we need one of those fancy Hg removal systems in order to protect BAHXs?

 

[SJones]

Somebody with the correct competence has to make the call: liquid elemental mercury at any time - yes or no? If nobody makes the call, either fit mercury removal or face the potential consequences a la Santos.

Steve Jones
Materials & Corrosion Engineer

http://www.linkedin.com/pub/8/83b/b04

 

[EdStainless]

I saw an on-platform separation vessel that had Hg in the bottom of it. An operator opened a valve and drained a little to show me. It was a Monel valve. When they replaced it later that day (after I pointed it out to an engineer) we took the valve apart and it crumbled in our hands.

Steve, thanks for the presentation.

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Plymouth Tube

 

[Corgas]

Thanks everyone for your input.

Corgas

 

[blacksmith37]

If you even think you have Hg (in Al equipment) ,I reccommend precautions. As I remember a "carbon" filter was effective (sorry I can't be more specific).